Abstract
The assumption that Skinner was a determinist requires some modification. Although Skinner may have favored determinism to varying degrees while he was advancing mechanistic accounts of behavior that were aligned with the views such as those of Loeb, Watson, and Russell, his advancement of determinism disappeared after his accounts became more closely aligned with selectionist views such as those of Mach, Peirce, and Dewey. This realignment entailed a switch from finding origins or sources for behavior in deterministic laws to finding origins or sources for behavior in random variation. Some sense of the conflict between these views appears early on in Skinner's writing, and arguments in favor of both of these views can be found in sources that Skinner identified in his writings. Although there were good reasons for Skinner to accept determinism when he was advancing a mechanistic behaviorism, there were also good reasons for Skinner to abandon determinism when he was advancing a selectionist behaviorism.